package com.pigotech.ptwo.widget;

import java.util.LinkedList;
import java.util.Queue;

import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.Scroller;

/**
 * 水平滑动的ListView
 * @author ghb
 * @version
 */
public class HorizontalListView extends AdapterView<ListAdapter> {

    protected ListAdapter mAdapter;
    /**左侧view的序号*/
    private int mLeftViewIndex = -1;
    /**右侧view的序号*/
    private int mRightViewIndex = 0;
    /**当前显示的序号*/
    protected int  mCurrentX;
    /**下一个显示的序号*/
    protected int  mNextX;
    private int mMaxX = Integer.MAX_VALUE;
    private int mDisplayOffset = 0;
    protected Scroller mScroller;
    private GestureDetector mGesture;
    private Queue<View> mRemovedViewQueue = new LinkedList<View>();
    private OnItemSelectedListener  mOnItemSelected;
    private OnItemClickListener mOnItemClicked;
    private OnItemLongClickListener mOnItemLongClicked;
    private OnScrollLeftListener mOnScrollLeftListener;
//    private OnScrollListener mOnScrollListener;
    /**数据是否改变*/
    private boolean mDataChanged = false;

    
    public HorizontalListView(Context context){
    	this(context, null);
    }
    
    public HorizontalListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    /**
     * 初始化视图
     */
    private synchronized void initView() {
        mLeftViewIndex = -1;
        mRightViewIndex = 0;
        mDisplayOffset = 0;
        mCurrentX = 0;
        mNextX = 0;
        mScroller = new Scroller(getContext());
        mGesture = new GestureDetector(getContext(), mOnGesture);
    }

    @Override
    public void setOnItemSelectedListener(OnItemSelectedListener listener) {
        mOnItemSelected = listener;
    }

    @Override
    public void setOnItemClickListener(OnItemClickListener listener) {
        mOnItemClicked = listener;
    }

    @Override
    public void setOnItemLongClickListener(OnItemLongClickListener listener) {
        mOnItemLongClicked = listener;
    }
    
    /**
     * 设置滑动到最左边监听器
     * @param listener
     */
    public void setOnScrollLeftListener(OnScrollLeftListener listener) {
    	mOnScrollLeftListener = listener;
    }

    private DataSetObserver mDataObserver = new DataSetObserver() {
	      @Override
	      public void onChanged() {
	          synchronized (HorizontalListView.this) {
	              mDataChanged = true;
	          }
	          invalidate();
	          requestLayout();
	      }
	
	      @Override
	      public void onInvalidated() {
	          reset();
	          invalidate();
	          requestLayout();
	      }
	};

    @Override
    public ListAdapter getAdapter() {
        return mAdapter;
    }

    @Override
    public View getSelectedView() {
        // TODO: implement
        return null;
    }

    @Override
    public void setAdapter(ListAdapter adapter) {
        if (mAdapter != null) {
            mAdapter.unregisterDataSetObserver(mDataObserver);
        }
        mAdapter = adapter;
        mAdapter.registerDataSetObserver(mDataObserver);
        reset();
    }

    private synchronized void reset() {
        initView();
        removeAllViewsInLayout();
        requestLayout();
    }

    @Override
    public void setSelection(int position) {
        // TODO: implement
    }

    private void addAndMeasureChild(final View child, int viewPos) {
        LayoutParams params = child.getLayoutParams();
        if (params == null) {
            params = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
        }

        addViewInLayout(child, viewPos, params, true);
        child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST), MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));
    }


    public interface OnScrollLeftListener{
    	/**
    	 * 滑动到了最左边
    	 */
    	void onScrollLeft();
    	/**
    	 * 滑出了最左边
    	 */
    	void onScrollOutLeft();
    }

//    public void setOnScrollListener(OnScrollListener onScrollListener) {
//        mOnScrollListener = onScrollListener;
//    }

//    public interface OnScrollListener{
//        void onScrollStateChanged(AbsListView view, int scrollState);
//        void onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount);
//    }
    
    @Override
    protected synchronized void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        // 滑动到最左边回调方法
        if(mOnScrollLeftListener != null){
        	if(mScroller.getCurrX() < 30){
        		mOnScrollLeftListener.onScrollLeft();
        	} else {
        		mOnScrollLeftListener.onScrollOutLeft();
        	}
        }
        
        if (mAdapter == null) {
            return;
        }

        if (mDataChanged) {
            int oldCurrentX = mCurrentX;
            initView();
            removeAllViewsInLayout();
            mNextX = oldCurrentX;
            mDataChanged = false;
        }

        if (mScroller.computeScrollOffset()) {
            int scrollx = mScroller.getCurrX();
            mNextX = scrollx;
        }

        if (mNextX <= 0) {
            mNextX = 0;
            mScroller.forceFinished(true);
        }
        if (mNextX >= mMaxX) {
            mNextX = mMaxX;
            mScroller.forceFinished(true);
        }

        int dx = mCurrentX - mNextX;

        removeNonVisibleItems(dx);
        fillList(dx);
        positionItems(dx);

        mCurrentX = mNextX;

        if (!mScroller.isFinished()) {
            post(new Runnable() {
                @Override
                public void run() {
                    requestLayout();
                }
            });

        }
    }

    private void fillList(final int dx) {
        int edge = 0;
        View child = getChildAt(getChildCount() - 1);
        if (child != null) {
            edge = child.getRight();
        }
        fillListRight(edge, dx);

        edge = 0;
        child = getChildAt(0);
        if (child != null) {
            edge = child.getLeft();
        }
        fillListLeft(edge, dx);

    }

    private void fillListRight(int rightEdge, final int dx) {
        while (rightEdge + dx < getWidth() && mRightViewIndex < mAdapter.getCount()) {
            View child = mAdapter.getView(mRightViewIndex, mRemovedViewQueue.poll(), this);
            addAndMeasureChild(child, -1);
            rightEdge += child.getMeasuredWidth();

            if (mRightViewIndex == mAdapter.getCount() - 1) {
                mMaxX = mCurrentX + rightEdge - getWidth();
            }

            if (mMaxX < 0) {
                mMaxX = 0;
            }
            mRightViewIndex++;
        }

    }

    private void fillListLeft(int leftEdge, final int dx) {
        while (leftEdge + dx > 0 && mLeftViewIndex >= 0) {
            View child = mAdapter.getView(mLeftViewIndex, mRemovedViewQueue.poll(), this);
            addAndMeasureChild(child, 0);
            leftEdge -= child.getMeasuredWidth();
            mLeftViewIndex--;
            mDisplayOffset -= child.getMeasuredWidth();
        }
    }

    private void removeNonVisibleItems(final int dx) {
        View child = getChildAt(0);
        while (child != null && child.getRight() + dx <= 0) {
            mDisplayOffset += child.getMeasuredWidth();
            mRemovedViewQueue.offer(child);
            removeViewInLayout(child);
            mLeftViewIndex++;
            child = getChildAt(0);

        }

        child = getChildAt(getChildCount() - 1);
        while (child != null && child.getLeft() + dx >= getWidth()) {
            mRemovedViewQueue.offer(child);
            removeViewInLayout(child);
            mRightViewIndex--;
            child = getChildAt(getChildCount() - 1);
        }
    }

    private void positionItems(final int dx) {
        if (getChildCount() > 0) {
            mDisplayOffset += dx;
            int left = mDisplayOffset;
            for (int i = 0; i < getChildCount(); i++) {
                View child = getChildAt(i);
                int childWidth = child.getMeasuredWidth();
                child.layout(left, 0, left + childWidth, child.getMeasuredHeight());
                left += childWidth + child.getPaddingRight();
            }
        }
    }

    public synchronized void scrollTo(int x) {
        mScroller.startScroll(mNextX, 0, x - mNextX, 0);
        requestLayout();
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
    	getParent().requestDisallowInterceptTouchEvent(true);
        boolean handled = super.dispatchTouchEvent(ev);
        handled |= mGesture.onTouchEvent(ev);
        return handled;
    }

    protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        synchronized (HorizontalListView.this) {
            mScroller.fling(mNextX, 0, (int) -velocityX, 0, 0, mMaxX, 0, 0);
        }
        requestLayout();
        return true;
    }

    protected boolean onDown(MotionEvent e) {
        mScroller.forceFinished(true);
        return true;
    }

    private SimpleOnGestureListener mOnGesture = new SimpleOnGestureListener() {
           @Override
           public boolean onDown(MotionEvent e) {
               return HorizontalListView.this.onDown(e);
           }

           @Override
           public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
               return HorizontalListView.this.onFling(e1, e2, velocityX, velocityY);
           }

           @Override
           public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
               synchronized (HorizontalListView.this) {
                   mNextX += (int) distanceX;
               }
               requestLayout();

               return true;
           }

           @Override
           public boolean onSingleTapConfirmed(MotionEvent e) {
               for (int i = 0; i < getChildCount(); i++) {
                   View child = getChildAt(i);
                   if (isEventWithinView(e, child)) {
                       if (mOnItemClicked != null) {
                           mOnItemClicked.onItemClick(HorizontalListView.this, child, mLeftViewIndex + 1 + i,
                                   mAdapter.getItemId(mLeftViewIndex + 1 + i));
                       }
                       if (mOnItemSelected != null) {
                           mOnItemSelected.onItemSelected(HorizontalListView.this, child, mLeftViewIndex + 1
                                   + i, mAdapter.getItemId(mLeftViewIndex + 1 + i));
                       }
                       break;
                   }

               }
               return true;
           }

           @Override
           public void onLongPress(MotionEvent e) {
               int childCount = getChildCount();
               for (int i = 0; i < childCount; i++) {
                   View child = getChildAt(i);
                   if (isEventWithinView(e, child)) {
                       if (mOnItemLongClicked != null) {
                           mOnItemLongClicked.onItemLongClick(HorizontalListView.this, child, mLeftViewIndex
                                   + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i));
                       }
                       break;
                   }

               }
           }

           /**
            * 判断点击落点是否在指定的View内部
            * @param e
            * @param child
            * @return
            */
           private boolean isEventWithinView(MotionEvent e, View child) {
               Rect viewRect = new Rect();
               int[] childPosition = new int[2];
               child.getLocationOnScreen(childPosition);
               int left = childPosition[0];
               int right = left + child.getWidth();
               int top = childPosition[1];
               int bottom = top + child.getHeight();
               viewRect.set(left, top, right, bottom);
               return viewRect.contains((int) e.getRawX(), (int) e.getRawY());
           }
     };
}
